Sulfonate detergent compositions of improved foam characteristics



United States Patent'O SULFONATE DETERGENT COMPOSITIONS OF IMPROVED FOAM CHARACTERISTICS.

Henry Y. Lew, San Francisco, and Richard D. Stayner,

Berkeley, 'Calif., assignors to California Research-Corporation, San Francisco, Calif a corporation of Delaware No Drawing. Application June 29, 1956 Serial No. 594,702

3 Claims. 01. 252-152 The present invention relates to improved sulfonate detergent compositions.

Among the variety of synthetic detergents available on the market and competing withsoap for different laundering and industrial uses, the largest group is that of alkylbenzene sulfonate detergents. These highly efficient the neutralized material (slurry);is reduced by finally obtained detergent product, the active alkylbenz enef sulfonate material is formed by branched-chain C -C monoalkylbenzene sulfonate, among which those containing C C alkyl chains usually preponderate. It is observed that aqueous solutions of these branched-chain monoalkylbenzene sulfonates, whether employed alone or in combination with the conventional detergent salt builders, when agitated in the washing machines or dish- 2 sponding 1,2-glycols, for instance, n-hexadecane 1,2- glycol.

It was, therefore, entirely unexpected to discover that the foam of dilute aqueous solutions of branched-chain C -C monoalkylbenzene sulfonates in the range of concentrations from 0.05 to 0.5%, conventional in the laundering art, can be markedly improved in quality and ren dered stable and persistent under the conditions of agita tion by combining these monoalkylbenzene. s-ulfonateswith from about 2 to about 20% by weight thereof, of a sulfonated C -C (and preferably C -C saturated fatty acid anilide (N-acyl sulfanilate), and further combining the resulting mixture of sulfonates with from about 2 to about 20% by weight thereof,'of a saturated aliphatic alcohol from the group consisting of C14-C16 normal monohydric aliphatic alcohols and 1,2-glycols.

When detergent compositions consisting essentially of;

the aforementioned three components: alkylbenzene sulfonate, N-acyl sulfanilate and an aliphatic saturatedalcohol or 1,2-glycol, within the aforegoing ranges of proportions, are dissolved in aqueous solutions for the purpose of washing soiled articles such as fabrics, clothes and dishes, a stable, good-quality foam is produced and persists despite the vigorous agitation of the washing "solution in the corresponding machine or device. In view of the low solubility in water of sulfonated higher saturated fatty acid anilides (N-acyl sulfanilates) of the order of less than 0.1% at room temperature, they produce a very "flo'w foam or no foam at all,'either alone or in combination' with higher saturated aliphatic alcohols, upon being dissolved in water and agitation. When added to branched-chain C -C monoalkylbenzen'e sulfonates the C -C N-acyl sulfanilates fail completely to enhance washers, form at first large volumes of copious suds which rapidly collapse, however, under the conditions of agitation and in contact with soil, owing to a weak,-lacy texture of these suds. This inability of producing 'satisfac: tory, stable, soap-like suds throughout'the complete washing cycle represents a serious drawback in the] eyes of a large fraction of the consumer public who often consider the foam to be an index of the washing efliciency and a measure of the washing material (soap or synthetic detergent) necessary for effective soil removal. f

A large number of compounds thought likely to improve the foam behavior of the aforementioned monolalkylbenzene sulfonate detergents have been tried in the past, in most instances, without success. Moreover, the

costs of many of the proposed additives were too high,

rendering their application in the amounts adequate to attain the desired improvement uneconomical. Higher saturated aliphatic alcohols, for instance, normal Cg-C13 saturated aliphatic alcohols have been reported in the art as.su ds boostersffor alkyl sulfate detergents and sulfated and sulfonated aliphatic acyl-containing detergents, such as C C fatty acid monoglyceride monosulfates. However, addition of these alcohols tobranched-chain mono alkylbenzene sulfonate detergent compositions failed to occasion any significant improvement in the stability, quality and persistence of the foam. As an example, addition of 10% by weight of normal hexadecanol to a C C branched-chain monoalkylbenzene sulfonate detergent appears to exert a defoamingaction in an agitated aqueous solution thereof, rather than to have a stabilizing eifect on the foam. The same ineffectiveness with respect'to the improvement of foam Jstabilit'y, quality and persistance of the aforesaid sulfonate detergents is observed with other higher saturated aliphatic alcohols, such as t dodecanol, n-tetradecanol, n-octadecanol and correthe quality, stability or persistance of the foam of aqueous solutions of the resulting blends. Therefore, the improvement in foam performance of'branched-chain C -C monoalkylbenzene sulfonate'detergents achieved by combining with them N-acyl sulfanilates and saturated c c aliphatic alcohols is altogether'surprising.

The alkylbenzene sulfonate components of the improved composition of our invention are branched-chain C -C monoalkylbenzene sulfonates, and predominantly the C C monoalkylbenzene sulfonates. These sulfonate materials are manufactured in accordance with the procedures known in the art, the process described in the- U. S. Patent 2,477,383 to A. H. Lewis being particularly suitable. Although any water-soluble, detergent branchedchain alkylbenzene sulfonate may be employed in formulating the compositions-of our invention, sodium salts are usually preferred," I V The sulfanilate components are prepared in any con venient manner, for instance, by reacting a suitable fatty acid with aniline ora methyl-substituted aniline, sulfonating the reaction product and neutralizing to form a salt, sodium salts being again preferred. The C -C saturated straight-chain N-acyl sulfanilates are moder-. ately crystalline, flaky materials, varying in color from amber to white in accordance with the degree of their purity. Typical representatives of these sulfanilates are: N-lauroyl sulfanilate, N-palmitoyl sulfanilate, N-stearoyl- N-methyl sulfanilate, and the like.

The saturated normal aliphatic alcohol component may be either a C C straight-chain monohydricalcohol or a C C straight-chain 1,2-glycol.

The actual formulation of the improved detergent compositions of our invention offers no particular problem. The three components'are slurried together, and the slurry is reduced to the desired form or particle size by conven-.

tional drying techniques.

employing the conventional detergent salt builder's'of'tho Patented Feb. 17, .1959.

sodium carbonate, sodium tripolyphosphate, tetrasodium pyrophosphate, sodium silicate, borax, etc. From 60 to 90% by weight of these builders, preferably as sodium salts, may be present in each 100 parts by weight of the finished detergent formulation. Of course, some sodium sulfate builder is present with the alkyl-benzene sulfonate component because of the usual methods for the preparation of this latter, Other conventional additives to detergent formulations, such as anti-caking agents, optical bleaches, corrosion inhibitors (e. g., Na SiO extenders and preventives of soil redeposition (e. g., carboxymethyl cellulose or derivatives of oxidized cellulose), skin emollients and anti-irritants (e. g., N-alkylglycines and N-alkyl diglycines), perfume and coloring may be present in small amounts, rarely exceeding a total of 5% by weight, based on the solids content of the formulation, and in all events in such amounts as not to interfere with the improved foam performance.

The superior foam performance of the detergent composition of the invention was verified by testing the foam stability and quality of aqueous solutions thereof in the laboratory. In a representative test series, the essential three components: the alkylbenzene sulfonate, the N-acyl sulfanilate and the aliphatic alcohol took up from about 20 to 22% by weight of each 100 parts of the dried built detergent formulation. The builders and additives cetyl alcohol being used in the larger proportion of the runs because of its ready availability.

Water from the laboratory tap was employed to prepare test solutions of 0.15% concentration. This water had a hardness of 50 p. p. m., calculated as CaCO and MgCO in a weight ratio of 2:1." In each test run, 500 ml. of the solution at 120 F. was introduced into a two-liter beaker, and the contents of the beaker were then agitated by means of a propeller-type stirrer for one minute. At the end of this period, foam height in millimeters was measured and the foam quality and stability observed. The agitation was resumed and, after fifteen minutes, the foam height, quality and stability were again determined.

Stability was rated by watching the rate of foam decay under mechanical stress, namely, when blowing on a small volume of foam gently with air. Where the surface bubbles of the foam withstood blowing and did not collapse, the stability was rated Good. Where the foam collapsed rapidly, the stability was rated Poor. Intermediate stabilities'were rated as Fair.

Quality of the foam was considered to be Good when it was'made up of small-size dense-bodied bubbles of a high bulk viscosity and presented a uniformly white, opaque texture. Foam of Poor quality was formed by large-size bubbles, was lacy, grayish in color, relatively transparent and displayed a low bulk viscosity. Foams intermediate in quality between Poor and Good were rated Fair. I

Foam evaluation tests Sulfanilate Alkylben- Alcohol Foam height zene in mm. Run sulionate Stability Quality N o. in percent Kind In percent byweight Kind In percent Alter} After by weight by weight min. min.

2 2 64 56 Good. Good 0. 5 0. 87 65 2. 18 2. 82 62 51 2 2 60 3. 8 1. 2 68 30 1 0 92 3 0 86 28 10 2 18 i5 10 0 28 11 10 2 24 12 5 2 3O 24 2 2 68 63 1 1 68 62 2 0 72 8 2 2 74 02 S0 66 2 2 48 38 2 2 63 15 D 1 2 67 2 1 70 58 D 21' do 1 4 22 15 22.... N-stearoyi, N-methyl 2 1. 5 83 67 23 N-lauroyl 2 2 64 56 I 24h". N-stearoyl 2 2 68 G3 25. d0 1 2 67 60 26 2 42 10 N-stearoyl, N-methyl 3 2 70 50 air. N-stearoyl 20 2 16 0 No foam. No (0am 1 Mixture of Cit-Ora aliphatic alcohols derived ironi tallow by catalytic hydrogenation, On; alcohol being the major component were: 30% of sodium tripolyphosphate, 20% of tetrasodium pyrophosphate, 5% of N grade liquid commercial sodium silicate and the remainder to make up 100% by weight was sodium sulfate. In all tests, sodium C C polypropylene benzene sulfonate was employed as a typical branched-chain alkylbenzene sulfonate detergent whose foam ordinarily lacks the required quality and stability. N-lauroyl sulfanilate, N-stearoyl sulfanilate and N-stearoyl, N-methyl sulfanilate were selected as typical representatives of the operative group of C -C Nj-acyl sulfanilates and combined withthe'alkylbenzene sulfonate component in the proportions within the range specified hereinbefore. Saturated aliphatic alcohols, both the operative (I -C alcohols and (for the purpose of comparison) the inoperative'ones outside the C -C The tabulated data unambiguously illustrate the superior foam performance of the three-component detergent mixture of the present invention over the formulations in which the only active detergent component is a branched-chain alkylbenzene sulfonate (run No. 16), over formulations in which a saturated C -C normal aliphatic alcohol is added to the detergent alkylbenzene sulfonate employed alone (run No. 26), and over the formulations in which a C -C N-acyl sulfanilate in amounts ranging from about 2"to about 20% by weight is addedto'the alkylbenzenesulfonate detergent in' the absence of the saturated aliphatic C -C alcohol or 1,2- glycols (runsNos. 6, 7 and 14). Sulfanilates'employed alone, owing to their low solubility, are totally incapable of forming the desired suds. Their'combinations were employed in the proportions specified hereinabove, with C C aliphatic alcohols are likewise incapable branched-chain alkylbenzene sulfonate, sulfanilate and alcohol, the sulfanilate or the alcohol components are present in amounts outside the preferred operative ranges specified hereinbefore, a poor foam performance invariably results (runs Nos. 2, 5, 8, 10, 11 and 21).

The three-component detergent formulation prepared in accordance with the invention produces stable, goodquality suds when employed in dilute aqueous solutions to wash soiled laundry in automatic and non-automatic agitator-type washing machines, and these suds persist throughout the complete washing cycle, usually of at least 20 minutes duration. At the same time a very satisfactory cleansing action is achieved. A similar effectiveness with respect to the foam stability and persistence and a satisfactory cleansing action is achieved in employing the formulation of this invention to wash dishes in automatic dishwashers.

We claim:

1. A built detergent composition of superior foam 7 characteristics consisting essentially, by weight, of about 100 parts of a branched chain C C alkylbenzene sulfonate sodium salt detergent, about 2 to 20 parts of a saturated aliphatic alcohol selected from the group consisting of straight chain C -C saturated monohydric alcohols and 1,2-glycols, from about 2 to 20 parts of an N-acyl sulfanilate of the general formula wherein R is a straight chain alkyl group of 9 to 17 carbon atoms and R is a radical selected from the group consisting of hydrogen and methyl radicals, and about to based on said built detergent composition of inorganic sodium salt builders.

2. Composition according to claim 1 wherein the alcohol is a straight chain C -C saturated monohydric alcohol.

3. Composition according to claim 1 wherein R is hydrogen.

References Cited in the file of this patent UNITED STATES PATENTS 1,932,180 Guenther Oct. 24, 1933 2,166,315 Martin July 18, 1939 2,679,482 Ross May 25, 1954 2,731,422 Ross Jan. 17, 1956 2,746,931 Vitale May 22, 1956 

1. A BUILT DETERGENT COMPOSITION OF SUPERIOR FOAM CHARACTERISTICS CONSISTING ESSENTIALLY, BY WEIGHT, OF ABOUT 100 PARTS OF A BRANCHED CHAIN C9-CC15 ALKYLBENZENE SULFONATE SODIUM SALT DETERGENT, ABOUT 2 TO 20 PARTS OF A SATURATED ALIPHATIC ALCHOL SELECTED FROM THE GROUP CONSISTING OF STARIGHT CHAIN C14-C16 SATURATED MONOHYDRIC ALCHOLS AND 1,2-GLYCOLS, FROM ABOUT 2 TO 20 PARTS OF AN N-ACYL SULFANILATE OF THE GENERAL FORMULA 